Why Convert to MBR Disk Greyed Out and How to Quickly Fix It

When Need to Convert a GPT Disk to MBR

MBR, short for Master Boot Record, uses the Legacy BIOS and supports 4 primary partitions or 3 primary partitions plus 1 extended partition. And the maximum addressable storage space of the MBR partition table is 2TB.

GPT, short for GUID Partition Table, uses the UEFI BIOS and supports up to 128 primary partitions in Windows. GPT disks are no actual limit to the size of hard drives.

Both MBR and GPT disks are two popular partition styles on Windows-based computers. They are the standard for the layout of storage devices such as HDD or SSD.

In general, GPT is designed to break through the limitations of MBR, especially for the storage limitations. However, many users still prefer MBR over GPT as it is still more compatible and is supported by all Windows operating systems. It is still required in some cases, as listed below:

• If you’re installing 32-bit Windows, select MBR as the system disk.
• If you’re still using a very old Windows OS, choose MBR for the system disk.
• If you’re running Windows XP or earlier, even 64-bit, MBR is the only option for a system disk.
• If you receive the error message “Windows cannot be installed to this disk. The selected disk has a GPT partition style” during Windows installation.

If you need to convert GPT to MBR, you can open the Disk Management program. When you right-click on the GPT disk, you may find the option of Convert to MBR Disk is greyed out. Why does this problem occur? How to fix this problem? Please continue to read the following part.

MBR VS GPT (Focus on Difference and How to Convert Safely)

Convert to MBR Disk Greyed Out in Disk Management

When converting a GPT disk to MBR in Disk Management, some users may encounter the “Convert to MBR greyed out” error. Here is a true example below from the techpowerup.com:

I bought an external hard drive and finds out it uses GPT instead of MBR. My Windows XP can’t read that.  The Convert to MBR option is greyed out. However, if you want to convert a disk to MBR the disk can’t have any partitions.https://www.techpowerup.com/forums/threads/convert-gpt-to-mbr.116796/

Why Convert to MBR Is Greyed Out

The reason for “convert to MBR disk greyed out” is that the selected GPT disk contains partitions. If the selected disk has partitions, the “Convert to MBR greyed out” error will appear. So, you cannot convert the GPT disk to MBR if the disk is not empty.

Now, you have known the reason for the “convert GPT to MBR greyed out” issue. So, there are 2 ways to solve this problem.

How to Fix Convert to MBR Disk Greyed Out

To solve the “Convert to MBR Disk gray out” problem, you can delete all partitions before converting. Or you can convert directly to an MBR disk without data loss using a professional tool. You can convert the disk to MBR in the following 2 ways. The detailed steps are as follows:

Way 1: Convert to MBR Disk without Data Loss

First and foremost, we recommend using MiniTool Partition Wizard to convert GPT to MBR, because it will keep your data safe and intact. This means you can directly convert the hard disk instead of deleting any partition.

What’s more, MiniTool Partition Wizard is a reliable partition manager that can help you do many works such as converting FAT32 to NTFS without data loss, formatting hard drives, performing disk benchmarks, migrating OS to SSD/HD, recovering the lost partition, and so on.

Note: As mentioned above, MBR disk has a maximum partition size of 2TB. If you convert any GPT disks larger than 2TB to an MBR disk, you should confirm that the used space on the GPT disk does not exceed 2TB. Otherwise, extra data will be lost. If you want to convert a GPT disk with more than 2TB of data, you can transfer excess data or delete unimportant information before conversion.

Kind remind: If you want to convert the system disk to MBR, you’d better use MiniTool Partition Wizard Bootable Edition to convert the system disk and make a backup of the system disk beforehand.

Here, we take a non-system disk as an example to show you how to convert GPT to MBR without data loss.

MiniTool Partition Wizard FreeClick to Download100%Clean & Safe

Step 1: Install and launch MiniTool Partition Wizard to get its main interface.

Step 2: Select the target disk and choose Convert GPT Disk to MBR Disk from the left side panel. Or, you can right-click on the target GPT disk and choose Convert GPT Disk to MBR Disk from the pop-up menu.

Step 3: This interface is the preview of the conversion result. Click on the Apply button to execute the change.

Step 4: Tap the Yes button to confirm the conversion. Wait for the completion of disk conversion. Then click on the OK button finally.

Now, your GPT disk has successfully been converted to an MBR disk without data loss.

Way 2: Convert to MBR with Deleting Partitions

You can also convert to MBR disk via Disk Management or Diskpart. But using the two methods requires deleting all partitions on the disk, so you should back up all necessary data saved on the GPT disk to avoid data loss.

To back up all necessary data saved on the GPT disk, you can use the Copy Disk feature of MiniTool Partition Wizard to back up the whole disk. The steps are as follows:

MiniTool Partition Wizard FreeClick to Download100%Clean & Safe

1. Download and install MiniTool Partition Wizard on your computer. Then launch it and get the main interface.
2. Select the GPT disk and choose Copy Disk from the left panel.
3. Select the target disk to copy the content to and click Next. When you click Next, it will remind you all the data on the target disk will be deleted, so please make sure there is no important file in the target disk.
4. Select copy options based on your needs and click on Next to continue. Here you can keep the default options unchanged if you are using an MBR disk.
5. Read the information and click the Finish button in the pop-up window. Finally, click on Apply to execute the pending operations.

After you back up the whole disk, you can delete all partitions on the GPT disk without worrying about data loss. There are 2 ways to convert GPT to MBR using Windows built-in tools.

Way 1: Convert to MBR Disk via Disk Management

I believe most of you are familiar with using Windows Disk Management. With a clean interface, this utility is also easy to operate. You can use Disk Management to convert to MBR by deleting all partitions. Note that back up important data.

To convert to MBR disk via Disk Management, you can follow the steps below:

Step 1: Right-click on the volume on the disk that is going to be converted to MBR and choose Delete Volume.

Step 2: You will see a prompt saying that deleting this volume will ease all data on it. If you have a back, you can click Yes to go on.

 Step 3: After a while, the volume will be deleted. If there are two or more volumes on the hard drive, delete them one by one via the steps presented above.

Step 4: As the entire disk becomes an unallocated space. Right-click on the GPT disk and choose the Convert to MBR Disk option.

Once done, you can successfully convert GPT to MBR. Then, restore all data to the MBR disk.

Way 2: Convert to MBR Disk via Diskpart

Another quick way to convert a GPT disk to MBR is to use the Diskpart command, which also deletes all partitions. Therefore, you need to back up important data.

To convert to MBR disk via Diskpart, you can follow the steps below:

Step 1: First of all, you need to pay attention to the number of the disk which will be converted to an MBR disk.

Step 2: Type diskpart in the Search box. Then right-click on the diskpart and choose Run as administrator. Then click on Yes in the UAC window to confirm the operation.

Step 3: In the Diskpart window, type the following commands in order and press Enter after typing each command.

• list disk
• select disk * (* represents the number of the disk that you want to convert)
• clean
• convert MBR

Step 4: Once you see the prompt “Successfully converted the chosen disk to MBR format.” You have done now. Once that, type exit and close the Diskpart window.

Now, your GPT disk has been converted to an MBR disk.

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Bottom Line

The above content has discussed 3 ways how to fix the “convert to MBR to disk greyed out” issue. The first way helps you to convert GPT to MBR without data loss on the disk, but the other 2 ways require you to delete all partitions on the disk.

Obviously, MiniTool Partition Wizard, the professional disk management tool is the best way to help you resolve the “convert GPT to MBR greyed out” problem without data loss. It not only can convert GPT to MBR safely and effectively but also can convert MBR to GPT.

For any other opinions about this problem, you can leave a message in our comment area below. If you meet certain issues while using MiniTool Partition Wizard, you can send us an email via [email protected] to get a quick reply.